Air strikes killed at least 25 people, mostly civilians, in north-western Syria on Monday in the sixth week of a Russian-led military offensive that has claimed the lives of hundreds.
Residents and rescuers said planes, which monitors said were Russian Sukhoi jets, dropped bombs from a high altitude on the village of Jabala in southern Idlib province.
Rescue teams had so far pulled 13 bodies, including women and children, from the debris.
Russian jets were also behind raids that hit the town of Khan Sheikhoun, Kfar Batikh and other villages, which left at least another 12 civilians dead, a rescuer said.
The air campaign supported by Moscow since the end of April has killed more than 1,500 people, about half of them civilians.
Residents and aid agencies say the sustained campaign that has bombed schools and medical centres was meant to smash the spirit of civilians in opposition areas.
More than 300,000 people have fled the front lines to the safety of areas near the border with Turkey, the UN and aid agencies say.
The Russian-backed offensive has so far failed to make major inroads into rebel territory in northern Hama and southern Idlib provinces.
There, mainstream rebels backed by Turkey and militants are putting up fierce resistance in their last remaining bastion in Syria.
Russia and the Syrian army deny allegations of indiscriminate bombing of civilian areas or a campaign to paralyse everyday life in opposition-held areas.
They say they are fighting militants inspired by Al Qaeda.
Moscow blames the rebels for breaking a truce by hitting government-held areas.
It says Turkey has failed in its obligations to expel militants under a deal brokered last year, which created a buffer zone in the area.
Civilians in rebel-held areas, many of whom do not want to return to Syrian President Bashar Al Assad's one-party rule, look to Turkey, which has steadily built up a military presence as a protector against the Russian-led strikes.
North-west Syria, consisting of Idlib and parts of neighbouring provinces, has an estimated three million inhabitants, about half of whom had fled fighting elsewhere, the UN said.